Process and apparatus for converting hydrocarbons



Dec. 1?., 1930. J. c. MORRELL ET AL 1,783,257

PROCESS AND APPARATUS FOR CONVERTING HYDROCARBONS Filed Juiy 17, 1924 z l @iwf @mu in., f ,W. //M

Patented Dec. 2, 1930 UNITED 4,sua-TES,

,PATENT OFFICE` JACQUE C. MORRELL AND HARRY P. IBENNER, OF CHICAGO,A ILLINOIS, ASSIGNORS T0 UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION 0F SOUTH DAKOTA PROCESS AND APPARATUS FOR CONVERTING HYDROCARBONS Application filed July 17,

This invention relates to a process and apparatus for converting heavy hydrocarbon oils into lighter hydrocarbons, and refers more particularly to securing a maximum production of lighter hydrocarbons from heavy hydrocarbons by subjecting the oil to the action of heat under superatmospheric pressure to cause substantial vaporization, withdrawing the vapors and subjecting them to reflux condensation. The unvaporized residue is adapted to be withdrawn and pumped to a coking still, where the pressure is materially reduced, thus causing the lighter fractions to be released due to the latent heat contained therein. The lighter fractions and residue from the coking still are withdrawn and separated. The reflux condensate from the primary cracking operation may be returned and mixed with the residue being withdrawn from the primary cracking operation just prior to being acted upon by the pump for the purpose of agitating and maintaining the residue in a turbulent condition to assist in holding the freed carbon particles in suspension in said residue and withdrawing them in that condition to be passed to the coking still.`

In the drawings:

Fig. 1 is a diagrammatic side elevational view of an apparatus suitable for carrying out my invention, and

Fig. 2 is a sectional view of the reaction chamber, taken on the line 2-2 of Fig. 1.

In the cracking of hydrocarbon oils, it is desirable to lengthen single treatments to the longest possible period from an economical standpoint, owing to the loss and wastek of time on shut-downs.

The length of a run is usually determined by the amount of coke deposited during the cracking operation so that any process which aims at the prevention of coke deposition will substantially eliminate this difficulty. This is one of the primary objects of our invention.

Referring in detail to the drawings, the raw charging stock may be introduced from any suitable source under pump pressure to the raw oil feeding line 1 which communicates with a continuous coil of say 3 or 4 inch 1924. Serial No. 726,440.

pipe (not shown), seated in the side fired furnace 2, which may be heated by means of the burner 3. Theheated oil passes from the heating coils through the transfer line 4 controlled by the valve 5 into the top of'an enlarged vertical reaction chamber 6 where substantial vaporization will take place. The vapors evolved in this reaction chamber 6 may be withdrawn through the line 7 controlled by the valve 8.and introduced to the lower portion of a dephlegmating tower 9 of usual construction and equipped with suitable bales, as is usual ina construction of this character. Reflux condensation will take place in the refluxing tower 9 and the vapors which do not condense may be withdrawn from the upper portion thereof through the line 10 controlled by the valve 11 communicating with condenser 12. The condensed liquid passes out through the line 13 controlled by a valve 14 to a suitable receiver 15 equipped with liquid drawoff 16 in which is interposed valve 17. This receiver is also provided with a gas release pipe 18 provided with valve 19 and pressure gauge 20.

Returning now to the dephlegmating tower 9, the reflux may be withdrawn through the pipe 21 controlled by a valve 22 and may be introduced'into the raw oil charging line 1 to be mixed with said charging stock and returned to the heating coils for further treatment; or by proper manipulation of the valves 23 and 23', the'reflux may be diverted and passed to the line 24 which line communicates through a pump 25 with the line 26v in which is interposed a Valve 27. The line the unvaporized residue, may be introduced through the line 24.

Referring now to another feature of our invention, below the expansion chamber 6 is positioned a pump 30, which is preferably of the centrifugal type, although it must be understood that any standard pump may be used. The discharge .end of this pump may be connected to the pipe 31, in which is interposed valve 32 communicating with a coking still or stills 33 mounted in thefurnace 34. Adjacent this discharge pipe 31 is another line 35 controlled by valve 36. The coking still may. beprovided with la vapor outlet 37 controlled by valve 38 which communicates with the dephlegmator tower 39, which latter is provided with the vapor outlet 40 in which is interposed valve 41 communicating with condenser 12. From the condenser 12 the condensed liquid is led awa`y through the pipe 42 in which is interposed the valve 43, to a suitable receiver 44 having the liquid drawoff pipe 45 controlled' by valve 46.

The coking still may also be provided with a residue drawoff 47 controlled by valve 48, which residue drawo line may connect, as shown, with the line 35. The line 35 may terminate in a homogenizer 49, the outlet 50 of which may communicate with any suitable storage.

Referring now to the operation of the device, the raw'oil is charged through the inlet 1 and mixes with regulated amounts of re flux condensate being withdrawn through the pipe 21 and passed to the heating coils into the furnace 2. The oil is there subject,

ed to a cracking temperature of say 650 to 825 F., and maintained under a superatmospheric pressure to prevent substantial distillation taking place therein. This pressure may be from five pounds to several hundred pounds. The preheated oil passes through the transfer line 4 into the reaction chamber 6 and the vapors are withdrawn and dephleginated-in the tower 9. The heavy residual unvaporized oil is pumped from the bott-om of this reaction chamber, preferably having a conical shaped bottom to facilitate the complete removal of the residual oil, together with any suspended coke forming particles. Assisting this action there may be intioduced a spray of light oil such as reflux oil returned through the line 21 as heretofore ex plained. This oil may be cracked distillate bottoms or gas oil introduced from any eX- ternal source through the line 24, the arrangement being such that a washing action takes place upon the inside of the cone shaped bottom. In other words, the shape of the extremity 28 causes the oil to have a swirling action, thus maintaining the residue and light oil in a turbulent condition.

. The heavy residual oil instead of being passed to the coking still 33 may be withdrawn through the line 35, the valve 32 being closed and the valve 36 open and passed to a stabilizing zone 49 Where the suspended cokelike particles are stabilized in the residue, that is, more or less permanently suspended due to the stabilizing action. The stabilized residue may be then passed to storage, and it must be understood that the stabilizing zone may be dispensed with.

Vhen it is desired to introduce the residue into the coking still 33, the valve 36 is closed and the valve 32 open. Within this coking still, a partial separation of the lighter fractions will take place, due to the heat contained in the residuum, or it may be assisted by external heat. The lower boiling point fractions separated from the residuuin may be dephlegmated'in the tower, 39, which. is provided with the reflux return line 51, which may communicate with the light oil inlet line 24 for the purpose heretofore explained. The residue from the coking still may be withdrawn through the line 47 by means of a pump (not shown) and is preferably homogenized before being sent to storage. The coking still may be operated under a reduced'pressure relative to the reaction chamber 6, if found desirable by manipulation of the valve 32.

The withdrawal of the heavy unvaporized vresidual oils from the expansion chamber 6 by a positive means, prevents the settling of the coke-forming particles which accumulate to build up a coke mass. This action is assisted bv the washing of the sides of the reaction chamber with a lighter oil as explained.

rThe many advantages should be at once apparent, such as increasing theexibility of operation, prolonging the period of the run, avoiding the necessity and expense of frequent cleanouts and the economic advantages accruing to the operation.

We claim as our invention:

1. An improved method for preventing the accumulation of a substantially solid residue in the reaction chamber of an oil cracking apparatus, which consists in continuously mechanically expelling the liquid residue, while carrying the coke-like-particles resulting from the cracking reaction in suspension, directly from the bottom of the reactionI chamber and in preventing precipitation of the coke-like particles from the residue and adherence of such coke-like particles to the wall of the reaction chamber, prior to the mechanical expelling of the residue from the reaction chamber, by continuously intioduc` ing a stream of a relatively light gravity oil, under a mechanically imposed pressure, into the body of residue in said reaction chainber, at a point above the point at which the residue is mechanically expelled therefrom, and in so introducing said stream of light gravity oil to the reaction chamber that a motiom is imparted to the residue therein and that portion of the wall of the reaction chamber to which the coke-like particles normally adhere is constantly subjected to a flushing' action by said light gravity oil.v

2.l An improved method for preventing the accumulation of substantially solid residue in the reaction chamber of an oil cracln'ng apparatus, which consists vin continuously mechanically expelling the residue, while carrying the coke-like particles resulting from the cracking reaction in suspension, directly from the bottom of the reaction chamber and in preventing precipitation of coke-like particles from the residue, prior to its mechanical expulsion from the reaction chamber, by.

continuously introducing a stream of a relatively light condensate produced in the cracking operation, under a mechanically imposed pressure, into the body of residue in said reaction chamber, and in so controlling the introduction of said stream of condensateV that a swirling motion is imparted to the residue in said reaction chamber and that por- -tion of the wall of the reaction chamber to paratus, which consists in continuously expelling the liquid residue, while carrying the coke-hke particles resulting from the cracking reaction in suspension, directly from the bottom of the reaction chamber and in preventing precipitation'of the coke-like particles from the residue and adherence of such coke-like particles to the wall of the reaction chamber, prior to the of the residue from the reaction chamber by continuously introducing a stream of a relatively light gravity oil into the body of residue in said reaction chamber, at a point above .the point at which the residue is expelled therefrom, and in so intmducing said stream of light gravity oil to the reaction chamber that a swir motion is imparted .to the residue therein and that portion of the wall of the reaction chamber to which the coke-like particles normally adhere is constantly subjected to a lushing action by said light gravity oil. Y y

4. An improved method for preventing the accumulation of substantially solid residue in the reaction chamber of an oil cracking apparatus, which consists in 'continuously expelling the residue, while carrying the coke-like particles resulting from the cracking reaction in suspension, directly from the bottom of the reaction chamber and in reventing precipitation of coke-like particles m the residue, prior to its expulsion from the reaction chamber, by continuously introducing a stream of a relatively light condensate produced in the cracking operation into the body of residue in said reaction chamber, and in so controlling the introduction of said stream of condensate that a swirling motion is imparted to the residue in said reaction chamber and that portion of the wall of the reaction chamber to which the coke-like particles normally adhere is constantly subjected to the iiushing action of the light condensate. 5. An oil cracking process which comprises passing a stream of the oil through a heating zone and heating the same therein to cracking temperature under -superatmospheric pres-A r moving the vapors and unvaporized oil om said reaction zone, reducing the pressure on said unvaporized oil to eli'ect distillation of a portion thereoand condensing the resultant vapors, and injecting a portion of the condensate directly and without passage through said heating zone into the unvaporized oil in said reaction zone to prevent the settling out of carbon from the oil in said reaction zone. L

6. In combination with the reaction chamber of an oil cracking apparatus, a vapor outlet for said chamber, a residue draw-oit at the lower portion of said chamber, a dephlegmator communicating with said vapor outlet,l means for removing from said dephlegmator reflux condensate formed therein, and means for injecting said reflux condensate into the lower portion of said chamber in such a manner as to impart a swirling motion to the unvaporizedoil therein and to flush the walls of said chamber to which cokelike particles normally adhere;

7. In combination with the reaction chamber of an oil cracking apparatus, a vapor outlet for said chamber, a residue draw-oil' at the lower portion of said chamber, a sll oommunicating with said residue draw-o, means for condensing vapors evolved in said still,v

and means for passing condensate from said condensing means to said reaction chamber and for injecting it thereinto in such a manner as to impart a swirling motion to the unvaporized oil therein and to iush the walls Aof said chamber to which coke-like particles normally adhere.

8. In combination with the reaction chamber of an oil cracking apparatus, a vapor outlet for said chamber, a residue draw-off at the lower portion of said chamber, a dephlegmater communicating with said vapor outlet, means for removing from said dephlegmator reiiux condensate formed therein, a still communicating with said draw-of, means for condensing vapors evolved in said still, means for injecting said reflux condensate and the condensate formed in said condenslng means into the lower portion of said chamber in such la manner as to maintain the unvaporized oil therein in swirling motion and to flush the Walls of said chamberto which coke-like particles normally adhere.

9. An oil cracking process which comprises passing a stream of the'oil through a heating zone and heating the same therein to cracking temperature under superatmospheric pressure, discharging the heated oil into a reaction zone maintained under superatmospheric pressure and in .which a separation of vapors and unvaporized oil takes place, separately removing the vapors and unvaporized oil from said reactiomzone, reducing the pressure on said unvaporized oil to effect distillation of a portion thereof, subjecting the vapors resulting from said distillation to reflux condensation and injecting the reflux condensate thus obtained without passage through said heating zone back into the unvaporized oil in said reaction zone to prevent the settling out of carbon from the oil in said reaction zone.

JACQUE C. MORRELL.

HARRY P. BENNER. 

